ABS greenlights ammonia turbine design for LNG carrier

Hanwha Power Systems (HPS) has received approval in principle (AiP) from classification society American Bureau of Shipping (ABS) for its ammonia fuel gas turbine conversion design intended for a 174,000-TEU LNG carrier.

IMAGE: Hanwha Ocean’s ammonia-powered LNG carrier concept Ocean 1. Hanwha Ocean

The approval confirms the technical and commercial viability of an ammonia-powered gas turbine propulsion system for marine applications, Hyoung-seok Kim, head of maritime solutions business division at HPS said.

It also confirms compliance with international safety standards for using ammonia as a fuel onboard vessels.

“With this AiP, Hanwha Power Systems has secured the foundation to propose retrofit packages for converting various ship types, including existing LNG carriers, to ammonia fuel,” HPS added.

Alternative propulsion for future fuels

HPS is working with shipbuilder Hanwha Ocean, both subsidiaries of South Korean conglomerate Hanwha Group, to develop this vessel.

Hanwha Ocean first introduced the concept of an ammonia gas turbine-powered LNG carrier in January last year, proposing to replace ammonia dual-fuel internal combustion engines (ICEs) on ships with a gas turbine to avoid reliance on pilot fuels such as diesel.

Ammonia as a fuel needs pilot fuel, like diesel, for ignition since ammonia's high auto-ignition temperature makes it difficult to burn readily or sustain combustion. Since the diesel pilot emits carbon dioxide, it undermines the ammonia's zero-emission potential.

“As existing internal combustion engines [ICEs] require 5% to 15% of pilot fuel, diesel, for the purpose of ignition, building a vessel free of carbon emissions requires a fundamentally different approach,” Dong Kwan Kim, vice chairman of Hanwha Group said last year.

To address this, HPS designed an ammonia pre-combustion combustor that partially oxidises ammonia before it enters the main combustion process. Research published by Harvard University indicates that such systems could improve the effectiveness of ammonia combustion in gas turbines.

ABS has already approved both, the vessel concept and the pre-combustion combustor technology, with its latest approval for the conversion system bringing the project closer to Hanwha Ocean’s 2028 debut goal.

Hanwha Ocean has indicated plans to deploy ammonia gas turbine-powered LNG carriers and container ships in the coming years. However, it has not disclosed any further details.

By Konica Bhatt

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